1. Field of the Invention
The present invention relates to a camera, and in particular, to an automatic focus (AF) adjusting apparatus thereof.
2. Description of the Prior Art
For an automatic focusing mechanism or an automatic focus adjusting apparatus in an imaging apparatus, such as a video camera, there have been developed such various methods for use in the automatic focus adjusting apparatus as an active method in which a radiation such as an infrared light or an ultrasound is irradiated onto an object for a distance measurement, and a passive method in which the focus is adjusted on the basis of a contrast signal attained from a video signal representing an image of the objective field. In these automatic focusing mechanisms, there has been a problem that when an obstacle such as a person or a car temporarily passes a way between a camera including the automatic focusing mechanism and an object to be shot during an operation of the automatic focusing mechanism, the focus point of the imaging system moves from the object to the obstacle. This problem is in general solved through an adoption of a designing technique in which the sensitivity the automatic focusing mechanism is lowered. In consequence, when a user of the camera desires to attain a focused state of an object at a high speed, the automatic focusing operation having such a slow response becomes to be insufficient, which leads to a problem that the focusing mode of the camera is required to be switched from the automatic focusing mode to the manual mode so as to manually adjust the focus on the object.